Many machines used for harvesting agricultural and horticultural crops, whether grown for food stuff of for industrial purposes, include an on-board facility for temporarily storing the harvested material. This is almost invariably, but not exclusively, the case with combine harvesters which have a grain tank and which are used to harvest cereals, oil seeds, pulses and some other crops which similarly produce seed as the harvested product. Harvesters for other crops have this storage facility to a varying extent.
Combine harvesters with two or more discharge channels and a diversion mechanism serving several separate outlets are known from GB 946,949 (Claas). Furthermore, machines which can sort a crop once harvested are also known, examples being described in U.S. Pat. No. 4,669,273 (Suggi-Liverani et al) and U.S. Pat. No. 4,410,091 (Cowlin and Helsby). This sorting stage generally takes place as a separate operation post-harvesting with each harvested item being analysed and then segregated.
Recent research has shown that many of the factors which are known to affect characteristics such as the yield and quality of harvested crops vary both between fields and within fields to the extent that the yield and/or the quality of the harvested material can show significant spatial variability.
Recent developments also allow the position of a machine within a field or area to be spatially determined, for example using dead reckoning or by triangulated reference to remove transmitters or reflectors, including the use of the satellite-based global positioning system (GPS) or the like.
The knowledge of within-field variability and the associated variation in yield, combined with the ability to determine position accurately, has lead to the mapping of the variables and to the concept of "Precision Farming". To date this has generally involved the planning, and perhaps variation, of inputs such as fertilisers and agrochemicals according to field reserves of nutrients of the occurrence of patches of weeds, for example. This type of technique is described in U.S. Pat. No. 4,630,773 (Soil Teq). It has also lead to the variable management or treatment of a field according to a map of the spatial variability of the crop yield in order to maximise output.
It will be appreciated that none of the known devices or techniques enable a crop to be automatically harvested selectively on the basis of pre-determined date or on the basis of real-time analytical data obtained by analysing crop "on-the-go". The prior art known to the applicant is indeed directed to the maximisation of yield from a particular field and to the separate and/or sorting of a crop after harvest under the direct control of the operator.
It is an object of the present invention to provide a method of segregating a crop as it is harvested on a predetermined basis.